240-million-year-old reptile fossil reveals a lost chapter before dinosaurs and crocodiles
A 240-million-year-old reptile discovered in Brazil is revealing what evolution looked like just before the rise of dinosaurs and crocodiles. The small predator had unusually positioned legs that may have allowed it to move more efficiently than many earlier reptiles. Its close relatives were previously known mostly from other continents, suggesting these ancient animals spread much farther…
Before dinosaurs and crocodiles emerged, their ancient relatives were undergoing critical evolutionary changes. In the aftermath of Earth's most significant extinction event, a newly discovered reptile species in Brazil's Rio Grande do Sul state sheds light on this period. Named Silescelida acristata, this Middle Triassic-period creature lived about 240 million years ago.
Found in Dona Francisca, part of the UNESCO Quarta Colônia Geopark, the fossil reveals insights into the evolution of archosauriformes, a group of reptiles that includes crocodiles and dinosaurs. Silescelida acristata, a small, four-legged animal akin to a modern alligator, played a role as a small predator in its ecosystem. Its femur shows semi-erect positioning, hinting at evolutionary advancements that would later aid archosaurs' success.
This discovery, made by researchers from various Brazilian universities, also reveals that Silescelida acristata's relatives were more geographically widespread during the Triassic than previously known. The fossil's history is equally intriguing, as a crucial fragment was lost for two decades before being rediscovered. Silescelida acristata's existence underscores the complexity and diversity of archosauriform evolution, illuminating the continent of South America's pivotal role in the early diversification of these lineage.
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